HELPFUL TIPS …
With some earlier versions of iOS this page did not display the map on Apple iOS devices, including Apple iPad, Apple iPhone and Apple iPod Touch. In case the problem arises with your device, a link is provided at the top of the map for Apple iOS devices that directs users to the map. The traffic layer does not always display upon landing on the map. Zoom in slightly or to a preferred level to see the traffic layer that shows congestion.

ABOUT TRAFFIC MAP DATA
When you choose to enable Google Maps with My Location, your phone sends anonymous bits of data back to Google describing how fast you’re moving. When Google combines your speed with the speed of other phones on the road, across thousands of phones moving around a city at any given time, Goggle can construct a traffic overlay of live traffic conditions on a Google map. See more on Google Official Blog The bright side of sitting in traffic: Crowdsourcing road congestion …